The present invention relates to an image forming unit and an image forming apparatus.
In a conventional image forming apparatus such as a printer, a copier, and a facsimile, an image is formed through the following process. First, a charge roller uniformly and constantly charges a surface of a photosensitive drum. An exposure device such as an LED head exposes the surface of the photosensitive drum to form a static latent image or a latent image thereon. A developing roller develops the static latent image to form a toner image. A transfer roller transfers the toner image to a sheet. After transferring the toner image, the sheet is transported to a fixing device, so that the fixing device fixes the toner image to the sheet. In the process, after transferring the toner image, part of the toner image may remain on the photosensitive drum, and a cleaning device removes the remaining toner.
A toner image supply roller is disposed to abut against the developing roller for supplying toner to the developing roller. A toner supply paddle is disposed at an upstream side of the developing roller to be freely rotatable in a cycle for supplying toner to the toner supply roller. An image forming unit (developing device) is formed of the photosensitive drum, the charge roller, the developing roller, the toner supply roller, the toner supply paddle, the cleaning device, and the like (refer to Patent Reference).
Patent Reference: Japanese Patent Publication No. 2005-172842
In the conventional image forming apparatus described above, when an image is formed continuously or a continuous printing operation is performed, it is possible to prevent a blurred portion. However, it is difficult to prevent visible fog in a white portion of a sheet, thereby deteriorating print quality.
In view of the problems described above, an object of the present invention is to provide an image forming unit and an image forming apparatus, in which it is possible to solve the problems of the conventional image forming unit and improve print quality.
Further objects and advantages of the invention will be apparent from the following description of the invention.